I have created a simple model here
When rendering it the end of it is cut off
How can I get the camera to render a longer distance?
The camera can only see the geometry that is within a range defined by the clipping distance.
Anything that that closer of further away from that distance range will be ignored.
With the camera object selected, increase its End clipping distance in Properties > Camera settings > Lens:
For 2.79 and earlier versions
To visualize the camera clip distance select the camera and enable Display > Limits.
For 2.8 enable Viewport Display> Limits